NORDAC LINK (SK 155E-FDS / SK 175E-FDS) – Users Manual for Motor Starters as Field Distributors
58 BU 0155 en-3520
4.3 AS Interface (AS-i)
This section is only relevant for device of type SK 1xxE-FDS-...-ASI, SK 1xxE-FDS-AUX, SK 1xxE-
FDS-AXS, SK 1xxE-FDS-ASS.
4.3.1 The bus system
General information
The Actuator Sensor Interface (AS-Interface) is a bus system for the lower field bus level. It has been
defined in the AS-Interface Complete Specification and standardised according to EN 50295,
IEC62026.
The transfer principle is a single-master system with cyclic polling. Since the Complete Specification
V2.1 , a maximum of 31 standard slaves using the device profile S-7.0., or 62 slaves in the
extended addressing mode using the device profile S-7.A. could have been operated with any
network structure at an unshielded two-wire line up to 100 m long.
Doubling the number of possible slave participants is realised by the double assignment of the
addresses 1-31 and the “A slave” or “B slave” labelling. Slaves in the extended addressing mode are
labelled by the ID code A and can be clearly identified by the master.
Devices with slave profiles S-7.0 and S-7.A. can be operated together within an AS-i network with
version 2.1 and higher (master profile M4), considering the address assignment (see example).
Permissible Not permissible
Standard slave 1 (address 6)
Standard slave 1 (address 6)
A/B slave 1 (address 7A) Standard slave 2 (address 7)
A/B slave 2 (address 7B) A/B slave 1 (address 7B)
Standard slave 2 (address 8)
Standard slave 3 (address 8)
Addressing is done via the master that also provides further management functions, or via a separate
addressing unit.
Device-specific information
The transfer of the 4-bit application data (per direction) is performed with effective error protection for
standard slaves with a maximum cycle time of 5 ms. Due to the higher number or participants, for
slaves in the extended addressing mode, the cycle time is doubled (max. 10 ms) for data sent from the
slave to the master. Extended addressing for sending data to the slave cause an additional doubling of
the cycle time to max. 21 ms.
The AS-Interface cable (yellow) transfers data and power.
It can supply for both the total need of control voltage (including control voltage for the device and any
connected sensors) and only the AS-Interface.
The supply of the device and any connected sensors can also be effected via an internal power supply
unit (“-HVS” option), via the “black two-wire line” (only possible with plug connector option: “-AUX” or
“-AXS” on option slot M8), or via a combination of both.
For the “-AUX” or “-AXS” option, the power supply unit (“-HVS” option) takes over a load-reducing
power supply function. For the “-ASI” and “-ASS” options, it depends on the AS-i supply voltage level.
Therefore, a load reduction cannot be assumed in each case.
“-AUX” or “-AXS” option (option slot M8): It is recommended, but not mandatory to effect the supply
via Protective Extra Low Voltage (PELV).
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